[trealira]

Are you saying that the way people naturally speak follows no rules whatsoever?

Linguistic descriptivism just means that, rather than hold up an ideal of a language and prescribe variants as wrong or right, linguists should simply describe the language based on its use. That doesn't mean that the language (or variants of it) has no grammatical rules. It just means that, rather than holding up some prestige variety as "the language," and unprestigious ones as "uneducated errors" that shouldn't be studied, that you study all of them and determine how they work and how they're developing.

No matter where you go, people speak languages with a limited set of phones, which are mapped onto morphemes, which combine by particular rules to form words, which themselves form larger groups, like phrases and sentences (often the line between these things isn't clear cut). But languages all have rules of their own.

To imply that descriptivism means languages have no rules would be like saying that physics has no laws, because a physicist makes empirical observations instead of just deciding whatever the laws of physics ought to be.

[webmaven]

I think the claim isn't that "language has no rules" but rather that the "rules" are far more context dependent and subject to change over time than would ordinarily be implied by the use of the word "rules".

Even at the lowest level of phonemes to morphemes, accents introduce a huge amount of variety, and it doesn't really get more orderly as you increase the level of abstraction.